[1] Illinois 351 is the former Business U.S. Route 51 through La Salle.

It crosses over the Illinois River on the Shippingsport Bridge south of La Salle and passes underneath the Abraham Lincoln Memorial Bridge as it climbs out of the Illinois River Valley.

Prior to 1963, US 51 originally traveled mostly along present-day IL 351.

as US 51 was rerouted west of LaSalle along present-day Illinois Route 251.

[5] The entire route is in LaSalle County.